Messages in this thread | | | Date | Fri, 18 Jan 2008 16:27:52 +0800 | From | Fengguang Wu <> | Subject | Re: [PATCH 00/13] writeback bug fixes and simplifications take 2 |
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On Thu, Jan 17, 2008 at 11:51:51PM -0800, Michael Rubin wrote: > On Jan 15, 2008 4:36 AM, Fengguang Wu <wfg@mail.ustc.edu.cn> wrote: > > Andrew, > > > > This patchset mainly polishes the writeback queuing policies. > > The main goals are: > > > > (1) small files should not be starved by big dirty files > > (2) sync as fast as possible for not-blocked inodes/pages > > - don't leave them out; no congestion_wait() in between them > > (3) avoid busy iowait for blocked inodes > > - retry them in the next go of s_io(maybe at the next wakeup of pdflush) > > > > The role of the queues: > > > > s_dirty: park for dirtied_when expiration > > s_io: park for io submission > > s_more_io: for big dirty inodes, they will be retried in this run of pdflush > > (it ensures fairness between small/large files) > > s_more_io_wait: for blocked inodes, they will be picked up in next run of s_io > > Quick question to make sure I get this. Each queue is sorted as such: > > s_dirty - sorted by the dirtied_when field > s_io - sorted by no explicit key but by the order we want to process > in sync_sb_inodes > s_more_io - held for later they are sorted in the same manner as s_io > > Is that it?
Yes, exactly. s_io and s_more_io can be considered as one list broken up into two - to provide the cursor for sequential iteration. And s_more_io_wait is simply a container for blocked inodes.
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